This invention relates generally to intraocular lenses and:, more particularly, to supplemental intraocular lenses, which can be placed in or on primary intraocular lenses to thereby change the effective optical power of the primary intraocular lens.
Vision is achieved in the human eye by transmitting an image through a clear outer portion called the cornea, and focusing this image via a natural lens onto a retina. When the natural lens looses its ability to clearly focus the image onto the retina through, for example, cataracts or injury, the quality of the focused image on the retina can be severely compromised.
An accepted treatment for a damaged natural lens is surgical removal of the natural lens and replacement of the natural lens with an artificial intraocular lens. One way to accomplish this procedure is to form a relatively long incision in the eye and remove the natural lens in one piece. A more popular method for removing the natural lens is to form a shorter incision in the eye and insert a probe or a phaco tip of a phacoemulsification instrument through the incision into the eye to break up the natural lens using ultrasonic energy. The lens fragments can then be aspirated from the natural eye through the relatively short phaco incision, and the phaco tip is then removed.
A preferred conventional method of removing a natural lens is accompanied with a subsequent implantation of a replacement intraocular lens in the same surgical procedure. A typical intraocular lens includes an optic usually having a diameter of about 6 mm, and fixation members coupled to (or formed with) the optic to fix the optic within the eye in the region of the extracted natural lens. These fixation members are generally in the form of at least two haptics, which may be flexible, elongated, open-ended loops that project from the edge of an optic portion of the intraocular lens. The fixation member may require additional incision links, depending upon the number, length, and configuration of the fixation member.
Intraocular lenses can be of two basic types, those having a hard or rigid optic formed, for example, of polymethylmethacrylate (PMMA) and those having a deformable optic which is constructed of a deformable material such as silicone, hydrogel, or an acrylic. When a hard intraocular lens is used, the small phaco incision must be enlarged to approximately the diameter of the hard optic, in order to permit the hard optic to be inserted through the incision. A deformable optic, on the other hand, may have a high elongation so that the optic can be causes to resiliently stretch and flex to assume a small cross-sectional configuration for passage through a small phaco incision.
Before implanting the intraocular lens, the physician must determine the intraocular lens power needed to achieve the desired refraction needs of the patient. This procedure can be difficult and inexact. Errors in measurement, inaccuracy of assumptions, and the difficulty of achieving precise placement of an intraocular lens make the physician""s selection of an exact corrective power highly prone to inaccuracies. Post-operative changes to the patient""s eye may also change the refractive power needed for the intraocular lenses in the patient. Consequently, the intraocular lens, after implantation, does not always provide a perfect vision correction. These post-operative refractive errors must often be corrected by a subsequent surgery to replace the implanted intraocular lens with another intraocular lens. A subsequent surgery involves re-entry into the eye through a new incision, removal of the initial intraocular lens, and implantation of a new intraocular lens. Needless to say, this conventional subsequent surgery procedure can be traumatic to the eye.
One approach for limiting the amount of trauma on the human eye caused by subsequent replacement of the intraocular lens is disclosed in Patel U.S. Pat. No. 5,366,502. This patent discloses supplemental intraocular lenses which may be subsequently attached to primary intraocular lenses after the initial implantation of the primary intraocular lens. Addition of a supplemental intraocular lens to a primary intraocular lens does not entail removal of the primary intraocular lens, and further requires a relatively small incision in the eye. The supplemental intraocular lenses, and most of the primary intraocular lenses, of this patent include specially configured connectors for mating the supplemental intraocular lens to the implanted, primary intraocular lens. These connectors can be in the form of hooks, projections, slots, and loops, which are suitable for securing the supplemental intraocular lens to the primary intraocular lens. These various securing means, however, can be complex and difficult to manufacture and implement. Additionally, the sizes of these supplemental intraocular lenses are often unnecessarily large, thus requiring a larger incision and more trauma to the eye.
New supplemental intraocular lenses and new primary intraocular lenses have been discovered. The present supplemental intraocular lenses may be attached to, conventional primary intraocular lenses, for example, using annular wrap-around clamps or adhesive. Thus, no special connectors need be included on the primary intraocular lens. This is a substantial advantage since the present supplemental intraocular lenses can be attached or secured to any primary intraocular lens. The primary intraocular lens need not be specially configured to accept the supplemental intraocular lens. Put another way, the primary intraocular lens need not be constructed to anticipate that a supplemental intraocular lens will be used. In addition, new primary intraocular lenses which have pockets for accommodating relatively small, supplemental intraocular lenses therein, and such small, supplemental intraocular lenses are provided. The present supplemental intraocular lenses are relatively easy to insert in the eye since, for example, they are relatively small and/or have no independent structure effective to fix the supplemental intraocular lens in the eye.
In one broad aspect, the present invention is directed to a supplemental intraocular lens including a central optic portion having at least one dioptic power, a peripheral zone surrounding the optic portion, and an added peripheral zone having wrap-around clamps for securing the supplemental intraocular lens to the primary intraocular lens. The primary intraocular lens may be conventional, for example, having no structure or structures specifically adapted to connect or couple with the supplemental intraocular lens. The optic portion and the peripheral zone of the supplemental intraocular lens contact a first primary intraocular lens face, and the wrap-around clamps contact a second primary intraocular lens face, which is substantially opposite to the first primary intraocular lens face. The peripheral zone can be slightly stretched to facilitate application of the wrap-around clamps around the periphery of the primary intraocular lens, and the wrap-around clamps are relatively rigid to facilitate a secure fit of the supplemental intraocular lens onto the primary intraocular lens. One or more, for example, two apertures formed in the supplemental intraocular lens accommodate the fixation member or members of the primary intraocular lens, to thereby prevent rotation of the supplemental intraocular lens, thus facilitating cylinder corrections.
According to another broad aspect of the present invention, the supplemental intraocular lens includes only a central optic portion and a peripheral zone. The peripheral zone has substantially no optical power, and has a reduced thickness relative to the thickness of a periphery of the optic portion. The supplemental intraocular lens is placed onto the first primary intraocular lens face, and the outer annular portion of the peripheral zone is attached to the first primary intraocular lens face. The outer annular portion of the peripheral zone may be secured to the first primary intraocular lens face using an adhesive. This supplemental intraocular lens may be replaced with a second intraocular lens by removing all of the first supplemental intraocular lens, except for the outer annular portion of the peripheral zone, and then placing the second supplemental intraocular lens, having a slightly smaller diameter, onto the first primary intraocular lens face.
In another broad aspect of the present invention, the primary intraocular lens has a pocket for accommodating the supplemental intraocular lens. The pocket is configured to expand upon insertion of the supplemental intraocular lens, to thereby reshape and change the refractive power of the primary intraocular lens. The supplemental intraocular lenses used for insertion into the pockets may be relatively small, and may have either convex or concave surfaces, or both.
These and other aspects of the present invention are apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.